Leather substitute



rmrrnn srnras PATENT orFioE.

JOHN D. PRINCE, OF sosron, MASSACHUSETTS.

LEATHER SUBSTITUTE.

No Drawing.

To all whom it may concern:

Beit known that I, JOHN D. PRINcE, a citizen of the United States, andresident of Boston, in the county of Suffolk and State of Massachusetts,have invented a new and useful Improvement in Leather Substitutes, ofwhich the following is a specification.

This invention relates to a sheet material designed to be used as asubstitute for leather, buckskin, chamois, and the like, and

' also as a substitute for rubber in many of its applications. It isparticularly directed to the industry of manufacturing boots, shoes andthe like, but it is of such a nature as to have a very wide range ofusefulness; some other applications which I may mention being floorcoverings, upholstery, vehicle tops and covers, waterproof clothing,piston packing, etc.

One of the particular features of advantage of this invention is thefact that it has a permanent fibrous appearance, so that it may, fromthe point of View of looks, fully satisfy the requirements of asubstitute for leather, buckskin, chamois, or other material of the samegeneral nature. In this respect my material is sharply distinguishedfrom rubber compounds, which have been in use, inasmuch as the latterhave, at the beginning and throughout their life, a glossy ap pearanceas contrasted with a fibrous one.

Again, my material may be used by shoe manufacturers in exactly the samemanner as leather is used today, no matter whether it be applied assoles, heels, or uppers. The very same machinery, dies, models and otherappliances may be used. It is also susceptible to the same finishingprocess, including the polishing, coloring, edging and stitch ing,Whether the latter be known as the channeling method, the McKay method,the stitched aloft method, the stitched down method, or any of the otherwell known methods of securing soles to uppers.

Furthermore, this material is about 20% cheaper than high grade leather,and on grinding tests, it has shown its wearing qualities to be 85%greater than that of the best scoured oak sole leather, and 73% betterSpecification of Letters Patent.

The material is about 100% more flexible than leather of correspondingthickness; it is waterproof, although it absorbs a suflicient amount ofmoisture to make it more desirable than rubber, particularly whenapplied to the manufacture of shoes or waterproof clothing, for thereason that it does not produce the so-called sweating effect. It willnot slip on wet pavements, nor will it adhere to clothing. It is muchmore resilient than leather, so that it is applicable to use in place ofthe so-called rubher heels, for the purpose of avoiding jars and shocks.It is heat proof and cold proof.

With this brief outline of the general nature and characteristics of thematerial, I will proceed to describe the manner in which it is made.

Broadly considered, the material is composed of a fiber which has beenground so Patented June 3, 1919. Application filed July 22, 1916. SerialN 0. 110,698.

as to be broken into short lengths, and 'rubber compounded with sulfur;the whole being suitably vulcanized into the desired sheet form andthickness. Other ingredients which are added in compounding the materialserve to enhance its valuable qualiies; and, in the best form of theinvention now known to me, the same is composed of cotton fiber,selected sheet Ceylon rubber, pure rubber gum, known as concho,reclaimed rubber or shoddy, pontianak, pulverized magnesia, red oxid ofiron, and sulfur.

I find cotton-fiber to be the most desirable of all, owing to itsstrength and availability, but, other vegetable fibers, such, forinstance, as hemp, flax, jute, sisal, wood fiber, straw or grasses, maybe employed.

In carrying out the invention, the cotton, as it is baled, isprovided'and subjected to a grinding process; a. 9., between heavyrollers in a machine commonly known as a rag mill, which is designed forgrinding fibrous material. The cotton is preferably ground in mass sothat the grinding process shortens instead of crushing the fiber, theeffect being a tearing apart as distinguished from a flat pressure. Thecotton is ground to lengths of approximately 1/100 of an inch and isthen ready for use in compounding my material. Thus, when I say in theclaims short length fiber, I refer to fibers of not more than about oneto ten one hundredths of an inch long.

To a batch aggregating approximately 20 pounds, the ingredientsmentioned are mixed in substantially the following proportions:

4.; pounds of cotton fiber, in its ground condition;

L pounds of selected sheet Ceylon rubber- 1% pounds of pure C-onchorubber gum;

9 pounds of reclaimed rubber shoddy;

1 pound of pontianak;

pound of pulverized magnesia;

g; pound red oxid of iron; and

1% pounds sulfur.

These ingredients are compounded and thoroughly milled between. heatedrollers into a mass, as is customary in compounding rubber, which iswell understood in the art.

I prefer to use the selected sheet Ceylon rubber because it is verystrong, clean and pure. However, other kinds of rubber can be used inits place, such, for instance, as up-river Para.

The Concho rubber is selected because of its great adhesiveness andelasticity. Furthermore, it is a good, pure rubber and blends well withthe other ingredients incorporated. But, in this case also, other rubbergums can be used, such, for instance,-

as Manocoba.

The pontianak, which is a byproduct of a resin, is particularlydesirable owing to .its adhesive properties, but other resins may beused in its place.

The reclaimed rubber, which is commonly referred toas shoddy, is aregular ingredient of rubber compounds, and is desirable for the purposeof cheapening the product.

The pulverized magnesia is, as is well understood, a drier, and isgenerally used in rubber mills. It has a suificient drying effect, islight in weight and a good filler. In place of it some such material aschalk flour could be used, if desired.

The red oxid of iron 18 used for the purpose of a coloring agent, but itcould be substituted by any other well known pigment material, such aslamp black, black carbon, chrome yellow, yellow ochre, Indian red, etc.

The sulfur is, as will be well understood,-

for the purpose of vulcanization.

" After the mixture has been compounded and milled as described, it maybe vulcan ized in any of the ordinary ways, such for instance, as in aflat sur ace press, or on rolls wrapped with wet cloth. A veryconvenient way is to vulcanize it in a press, the plates of which areblocked apart a sufiicient distance to give the finished sheet materialthe desired thickness. The vulcanization is preferably carried out at atemperature equivalent to 35 pounds steam pressure, and for a timeperiod of 25 minutes. This quick vulcanization, at a comparatively lowtemperature, is very desirable from the point of view of economy oftime, fuel and labor, and it also is advantageous as it minimizes thetendency of the heat of vulcanization to injure the natural oily or waxymaterial in the cotton fiber. The manner of vulcanizing will be wellunderstood to any one skilled in the art, Without further description.

After vulcanization, either one or both surfaces of the material may bebufied to remove any glossy appearance resulting from the action of theplatesin the vulcanizer, so as to provide a natural, fibrous appearance.This buffing may be accomplished by any of the ordinary methods commonlyemployed in rubber manufactories, and is well understood in theart.

Instead of simply vulcanizing the material into sheets, it may beassociated with cloth, such, for instance, as duck or sheeting, bycalendering, in a well known manner, the composition onto one or bothsurfaces of the cloth. The cloth thus calendered with the material, maybe subjected to heat for the purpose of vulcanization, after which itmay be applied to such uses as Waterproof clothing, uppers for shoes,upholstering or other cases where a very flexible leather or rubbersheet is required;

\Vithout setting forth at greater length the characteristics andadvantages of my invention, I may repeat that two of its greatestfeatures of value lie in the fact that it may be employed by themanufacturer in exactly the same way that leather isused, and that ithas, at the beginning, and during its whole life, a fibrous leatheryappearance.

In conclusion, it will be understood that 110 various changes may bemade in the ingredients and proportions specified; and in the method oftreating, compounding and vulcanizing the various substances, withoutdeparting from the spirit and scope of my 115 invention; hence I do notintend to be limited to details hereinbefore described except as theymay be specifically included in the claims.

What I claim is 1. A permanently fibrous material designed as asubstitute for leather and the like, comprising short length fiber, apure, clean rubber. and a strong and adhesive rub her, the same beingcompounded with sulfur a resin, and a drying agent, the Whole beingcompounded with sulfur and vulcanized.

3. A permanently fibrous material designed as a substitute for leatherand the like, comprising a short length fiber, a pure, clean rubber, astrong and adhesive rubber shoddy, a resin, a drying agent, andapigment, the same being compounded with sulfur and vulcanized. v

4. A permanently fibrous material designed as a substitute for leatherand the like, comprising short length fiber, selected sheet Ceylonrubber, gum Concho, shoddy,

